The invention relates phase-separated compositions comprising two miscible solvents. More specifically, the invention relates to compositions comprising liquid droplets of an internal phase comprising a solvent B and further compounds, said droplets being dispersed in an external phase comprising solvent A, wherein solvent A and solvent B are miscible. Such compositions find use in various technical fields, including encapsulation, vectorisation, protection of compounds, separations, and chemical reactions in a dispersed medium.
The invention also relates to a process for making capsules, or even multiple capsules, wherein such a composition is used. This process is simple, cost effective, and/or offers a new solution for encapsulating, vectorising, or protecting some compounds.
Various kinds of dispersions of objects in a liquid medium have been used for years. Various kinds of dispersions of objects in a liquid medium have been described in references. Dispersions of solid particles of various sizes in water are often referred to as particle dispersions or colloidal dispersions. Dispersions of droplets of a first liquid phase in a second liquid external phase, wherein the two phases are not miscible, are usually referred to as emulsions (if energy is added) or microemulsions (if the system is at a thermodynamical equilibrium). Use of dispersing agents or stabilizing agents, such as surfactants or amphiphilic copolymers, is known.
Dispersions of objects such as capsules are also known. Capsules are objets comprising a shell either empty or comprising inside at least one internal phase and/or additive (core). Examples of capsules dispersions include dispersions in water of vesicles comprising a core being an aqueous phase, and a shell being a membrane consisting of two organized layers of amphiphilic compounds comprising a hydrophilic moiety and a hydrophobic moiety. In vesicles, the hydrophobic moiety of one of the layers faces the hydrophobic moiety of the other layer.
The dispersions as described above find use in many fields. Examples include encapsulation, vectorisation and/or protection of compounds, for said compounds to be released, protected, and/or provided in an incompatible environment. Examples include also chemical transformations in a phase separated system, inside a dispersed object or at an interface. Examples include also separations of compounds and/or recovery of compounds. There is a need in enriching the art with dispersions comprising different phases and optionally further compounds, in different concentrations. There is also a need in providing products for reinforcement, strengthening, and/or modifications of mechanical properties of materials, such as elastomers or thermoplastics.
In preparing dispersions, multiblock copolymers have proved to be useful. Recent references teach the use of diblock copolymers for making vesicles. For example Discher et al. describe using polyphenyleneoxide-polyethylethylene [EO]40-[EE]37 block copolymers, in SCIENCE, may 1999, page 1143. They teach that using block copolymers allows controlling some properties of the membrane, such as mechanical properties. Yu et al. in Langmuir, 1999, 15, 7157–7167 describe using polystyrene-polyethyleneoxide block copolymers, and controlling the membrane structure. Shen et al. in J. Phys. Chem. B 1999, 103. 9473–9487 describe using polystyrene-polyacrylic acid [Styrene]310-[AA]52 block copolymers. Using polystyrene-polyacrylic acid block copolymers is also described by Yu et al. in Macromolecules, Vol 31, 1144–1154. Vesicles may be obtained by thin film rehydratation, or by adding water to a block copolymer dispersed in a solvent (self-formation). Vesicle structures are useful to encapsulate hydrophilic compounds.
In completely different objectives, it has been taught that two miscible solvents can phase separate by adding a polymer. However, such a phase separation does not result in a stable dispersion, and a collapse occurs.